Method of preserving rubber



Patented July .27, 1943 UNITED STATES ME HOD O i R N R BB r" 4 Robert ItfSibIeyLNitmQ assig nor to Mon;- v santo Chemical Company, Louis, -Mo., a.corl poration' of Delaware v N Drawing. Application June' -*2l; 1941',Serial g I "No; 399,231. "In' Ganada-FebruaryIE, 1939 f The present invention relates to the art of 'It has long been known that'such deterioration 1s Claiins. argest-8105 V "of twenty pounds steam pressure perisquare inch.

can be greatly retarded by treating the rubber 1 o superior class of antioxidants; for rubber;

The age-resisting characteristics of. a vula canized rubber product can be readily ascertained iby subjecting samples of thejvulcanized product infabomb to the action of air or oxygen under tion of the test..': 3

It has been discovered in accordancewith the present invention that the butyl. and amyl'resorcinols comprise 'a valuable group of antioxidants. Inthe preferred aspects of the invention there is employed a monoor di-amyl or butyl resorcinol wherein the alkyl groups are branched The new and preferred group of antities characteristicofthe preferred class ofmatee,

weight of antioxidant was added and the rubber stocks vulcanized in a press at the temperature Theiicured rubber products were then' artificially age'di-by' heating for fourhours in an air bomb -at 250 F.- and eighty pounds'air pressure -per "square inchn The'tensile strengths'of the aged rubber products were thencompared to those of the" base stock, 'i. e. containing no antioxidant,

I ll) ar'e'the ratios of the tensile strengths at break of; 'the'stocks containing an antioxidant tothose containing no antioxidant. Y, That is -to'-- saythe base stockis arbitrarily taken as 100 arid "the tensiles ofthe protected stocks divided by the depending upon thej conditensile of the base stock andfmultipliiad "100 elevated pressure. The aged rubber samples are 1 fto give ed-Co pa ve "mtin f "then examined and tested and the'testdata compared with the results obtained on testingthe a unaged rubber samples. The deterioration" in v y propertieseffected' as 'a result of the-oxidation Ratioofagedtehsilesin treatment isindicative 'of the resulttl'iat would j, f 1 j'Ahtioridaht V normally be expected of that particular'stock a'o mimcurc ifimimcute 'duringactualservice. Such a test is known-as theBierer-Davis aging test and producesan f -a I feet on. a vulcanized rubber stock comparable Di-tertiary g with thatresulting from several years o f-natural "M w- 7 aging of the rubber l; h e above data'show'that thpret'rte'dttitiss of materials impart appreciable resistance to aging 'to rubber compositionsq,"

A cured sample "of the iwhiterubber has; stock described aboveto'getherj with ysamp les of the reg stock containing. 1.0 part by] weight; of various substituted resorcinolsqwere exposed-to "therays of a sunfllamp. jAfter s'ixty hours exare summarized below. 1 ;J

posure comparisons were" made as to the" dis,- coloration. which had'ftaken place The results rials and are tobeunderstood as illustrating'the o invention and not limitative thereof, v Ammdant 0019f i f t i Arubber base stock was compounded comprisg 1 H I v 1 None Light yel10w. mg 1 v I v 2. Di-tertiary butyl'resorcinol Light yellowish brown-falmost -.s.Parts-b .welght t v w matchesbhnk- 45 3 Mono-tertiarybutylresorcinol LightyellowiShbroWh-slightl '1 t v;fiaikerflmitheflblammflg Zinc mn-dp I. 4 Mono-tert ar mylresorcmol, Lightigellowish brownmatch- LlthOIJOnG ,20 5. Di-secondary'amylresoreinoL.'Matihes blank. I

Sulfur 2, .1; :gs l lzi rlresorcin il gink,

I I substituted resorcinolsjareexceptionally resistant Tothe'base stocks iso' compounded 1.0 part by to discolorationf From the specific examples hereinbefore set forth it is shown that rubber compositionscontartar.anpncaagnfsem 631 116 a itud -Mam taining small proportions of the preferred class of materials markedly resist the deteriorating insisters oi this invention. The antioxidants or age-resiste'rs may be employed in "difier'ent proportions than herein described and in conjunction with other vulcanizing agents than those) specifically disclosed, for this inventipnf ;appl, cable generallyto pure rubber or rubber compos i I tions of the most varied nature. FiirtlierInbre,- the preferred class of materials may'be employed in rubber stocks in conjunction with other accelerators than those specifically shown. mthwaliyew ing differences in tensile and lmoduluyproprtiesi; but still exhibiting the desirable properties otthe class. I v

It is :to be und rsto d, thatzzthe term ftreatins emnlbyed in the appended; a ms s-usedini eneric. sense to inclu e.;e hc the inco po atin --Qr th.e pr ferred c ass of mater als i to. them! bery m ing qr. sim lar p ocess, r the r; addiit ons othe rub e ietex be lorseits; oasul ticnlo theia pl cat on the e f t thes r se f am s .Qi cr eor ulca izedt subhen Tt. e e r ifi 112- ;beri? ikewisereni ediin t e rla m tlma ne ic sen ctoxie inea s iu vu qamze l u .be qme a al wh c p ssesses -1 m n xt nsib lit cin er L ad .pq'u ed. :wi whe. piqn rt i i .ipmibi ret c ng to; pnmxii ate riis rig a si e an sh rewhe tiiei adli rem ve v include for'example india ru erre J I ber, balata and gutta percha. The invention is also applicable to synthetic rubbers having the above properties. a

The present invention is a continuation in part of. attendin appli n al .9, ..6' .fi d- November 27, l9 4 0, which is a continuation in N0.,,199.,34.. filed April 2,

1938. a Y I The present invention isfli'inited solely -by-the claims attached hereto as part of he presfent spse fiwi w than ix comprises treatinga rubb stituted in the nucleus-by t least one but less a three r nc ed 91 315 .a' k r snt ming rnorethanthree but less than six carbon gt'qmfssyp 4. The method oi preservin a rubber ivvnich comprises treating a, rubber with a resorcinol sub;-

t tu d hezn c eu b i eas w b t s than-three tertiary: alkyl groups conta ning 'rnore than three but lesssthan-six carbon atoms." t

5. The method: offpreservingv axrubber-which comprises treating a' rubberwith a resor c'inol sub stituteddn the nucleusfby at"l'e'a' st one but less than three secondary allgyl gro in e than 1ibuti'e'ssith n which comprises treating natural rubber with a resorcinol possessing the structure 1E0 where X and Y represent branched chain alkyl radicals containing more than three but less than a swa ms toms 7; The method of preserving natural rubber 1; which. comprises treating natural rubber with ditertiary bu-ty l "i e'sorjcinol.

'BJThe" niethod of preserving natural rubber which cqrg prises trgating natural rubber with dils econdary? amyl resorcinol.

9, The method of preserving natural rubber which comprises treating natural rubber with Amie-tert ar but lr ssssiept a e l Th vulea st l b PIQQ a pbt' inesimb ns: scrub e a d 511. 1 in the-p ese c 91. a W 9r 9 a h iQ th fi ky i mlp 99 in wme e han hree b t e s-than s1 ar stee 1 4 i l-" h v lcan z d rub r p u t bt ined by h at n a b rnd. su f n'th pres n e oiv s iiie Su uted in't e nu le s y a leas is niore'thaii ihree but, le n six carbon ato The" u n .ed rub e prqduct ain d b heati ambbei and. sul ur i he P e nc or. a refi r nfll llbs t t d 1 .1. nuc s b leas "one but 1ess than three secondaryalkyl groups containing more than three but less than; six

carbonatomswl 5 111;: vulcanized rubber product obtained by heating natural rubber and"suliur in-[the pres- -enceofa resorcinol'possessing the structure where X and Y represent branched chainal-leyl radicals contain-ingr'nbre' than -tl'-ii ee but= less than six carbon atoms T I 16.- 'lhevulcanized rubber 'p'roduct obtained by heating natural rubber and sulfur in the presence of di te'rtiary butyl resorcinol.

pres:-

ence of monortertiarv-butylresorcinol.

one but less than three alkyl groups'pontaining l'leiThexulcanized.rubbervproduct obtained -by 

